JP2004010003A - Travel control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a travel control device to improve the followability by the control in confirmity with to driver's feeling. <P>SOLUTION: Judging whether a leading vehicle is in slowdown state (step S4 to S6), and in the case of the slowdown state, even when there is an enough distance between vehicles, predetermined deceleration is set up (step S10 to S15), gradual deceleration is performed (step S8), and the travel control in confirmity with the driver's feeling is performed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a travel control device that detects a preceding vehicle and performs following travel while controlling the following distance.
[0002]
[Prior art]
2. Description of the Related Art There is known a travel control device that detects a preceding vehicle using a camera, a radar, or the like, and that travels following the vehicle while controlling the distance to the preceding vehicle. In such a traveling control device, when the traveling state of the preceding vehicle fluctuates, the traveling state of the host vehicle follows the traveling state, which is likely to cause a delay, and the following performance tends to deteriorate. The technique disclosed in Japanese Utility Model Laid-Open Publication No. 2-133800 is an example of a technique for improving the followability of the host vehicle, and changes the target inter-vehicle distance according to the acceleration / deceleration of the preceding vehicle. Thereby, followability and safety are improved.
[0003]
[Problems to be solved by the invention]
However, in this technology, since control is performed so as to maintain the target inter-vehicle distance, even when the preceding vehicle is decelerating, if the inter-vehicle distance is too wide, the own vehicle is accelerated, and the inter-vehicle distance is approaching. In such a case, even when the acceleration of the preceding vehicle is large, the vehicle decelerates and the control does not match the driver's feeling, so that the driver may feel uncomfortable.
[0004]
Therefore, an object of the present invention is to provide a travel control device in which the followability is improved by control that matches the driver's feeling.
[0005]
[Means for Solving the Problems]
In order to solve the above problem, a travel control device according to the present invention is a travel control device that detects a preceding vehicle and controls a following distance, based on a following distance, a relative speed, and a own vehicle speed between the preceding vehicle and the own vehicle. A target inter-vehicle distance and a target acceleration / deceleration state of the host vehicle are calculated, and the target inter-vehicle distance and the target acceleration / deceleration state are adjusted according to the acceleration / deceleration state of the preceding vehicle or the host vehicle.
[0006]
The target inter-vehicle distance, relative speed, the target inter-vehicle distance and the target acceleration / deceleration state are set according to the host vehicle speed, and the target inter-vehicle distance and the acceleration / deceleration state are set according to the acceleration / deceleration state of the preceding vehicle or the host vehicle. By performing the adjustment, it is possible to perform fine control that matches the driver's feeling.
[0007]
For example, even if the inter-vehicle distance to the preceding vehicle is greater than the target inter-vehicle distance, it is preferable to perform slow deceleration when detecting deceleration of the preceding vehicle. By performing slow deceleration, while maintaining a gentle approach to the preceding vehicle, inadvertent acceleration is suppressed, and the shift to the target inter-vehicle distance is continued in accordance with the driver's sense.
[0008]
In addition, it is preferable that the target inter-vehicle distance is set shorter than the other cases during the acceleration of the own vehicle, and the target inter-vehicle distance is set longer than the other cases during the deceleration of the own vehicle. As a result, traveling control that matches the driver's feeling can be performed.
[0009]
When the required acceleration is reduced during the throttle control, it is preferable to estimate the acceleration obtained when the throttle is fully closed, and to switch to the brake control when the required acceleration is lower than that. Further, when increasing the required acceleration during the brake control, it is preferable to estimate the acceleration obtained when the brake is off, and to switch to the throttle opening control when the required acceleration exceeds it. This makes it possible to smoothly switch between the throttle control and the brake control, particularly on a slope road.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate understanding of the description, the same components are denoted by the same reference numerals as much as possible in each drawing, and redundant description is omitted.
[0011]
FIG. 1 is a schematic diagram of a vehicle equipped with a travel control device according to the present invention, and FIG. 2 is a block diagram of the vehicle. The travel control device 60 includes a laser radar sensor 1 that irradiates a laser beam forward as a means for detecting a preceding vehicle and detects the reflected light at a front portion of the vehicle. The control ECU 2 detects the preceding vehicle and controls the traveling of the vehicle. The control ECU 2 includes a headway control ECU 20, an engine ECU 21, and a brake ECU 22.
[0012]
Among them, the engine ECU 21 controls the operation of the engine 3, and the control includes the operation control of the throttle motor 31 of the electronically controlled throttle. The brake ECU 22 controls the operation of brakes disposed on each wheel, and the braking force of each brake is controlled by controlling the hydraulic pressure applied by the brake actuator 4.
[0013]
The ECU 2 includes a wheel speed sensor 50 for detecting a wheel speed of each wheel, a hydraulic pressure sensor 51 for detecting a hydraulic pressure applied to each brake, a G sensor 52 for detecting a longitudinal acceleration of the vehicle, and a throttle opening. Each output of the throttle opening sensor 53 and the output signal of the laser radar sensor 1 described above are input.
[0014]
Next, the operation of the travel control device 60 will be described. FIG. 3 is a diagram illustrating a state of the preceding vehicle and the own vehicle. As shown in the figure, the preceding vehicle is represented by P and the own vehicle is represented by M. In this control, when the preceding vehicle P does not exist, the system is turned off. Note that steady traveling may be performed at a predetermined speed. On the other hand, if the preceding vehicle P is present, one that travels while maintaining the inter-vehicle distance, together with the match inter-vehicle distance Dr between the vehicle target distance Dt, the relative speed Vr (the vehicle M speed V _M - performing a control such as the vehicle speed V _P of the preceding vehicle _P) is zero.
[0015]
4 to 8 are flowcharts of specific control. The following control is carried out in cooperation with the ECU 2, more specifically, the headway control ECU 20, the engine ECU 21, and the brake ECU 22. It is executed repeatedly. The following running mode is released when the driver operates a brake pedal, an accelerator pedal, a shift lever, or the like, in addition to a case where a control switch (not shown) is turned off.
[0016]
First, the main processing shown in FIG. 4 will be described. In step S1, the outputs of the laser radar sensor 1, the wheel speed sensor 50, the oil pressure sensor 51, the G sensor 52, and the throttle opening sensor 53 are read. In step S2, based on the loaded output value to calculate a vehicle speed V _M brake ECU22 from the output value of the wheel speed sensor 50, vehicle control ECU20 is to determine whether the preceding vehicle P, there is the preceding vehicle P If it is determined that the vehicle is running, the inter-vehicle distance Dr to the preceding vehicle P and the relative speed Vr and relative acceleration Gr of the own vehicle M to the preceding vehicle P are calculated.
[0017]
In step S3, a target acceleration Gt of the vehicle M for performing the following control is calculated. FIG. 5 is a flowchart showing details of the Gt calculation. First, in step S21, a base inter-vehicle time Δtb is set. Here, the base inter-vehicle time Δtb is equivalent to the base inter-vehicle distance, and means that the vehicle M reaches the position of the preceding vehicle P after Δtb when traveling at the current speed. It is set by. In addition, when using the constant speed traveling, the driver sets the set vehicle speed, and the base inter-vehicle time Δtb is set by the s-crotch control ECU 2 based on the set vehicle speed, the actual inter-vehicle distance, and the actual vehicle speed VM. You.
[0018]
In step S22, the value Gtod of the target acceleration set in the previous time step is compared with a threshold value Gth2. When Gtold is equal to or smaller than Gth2, the process proceeds to step S23, and Gtod is compared with -Gth2. If Gtod is equal to or larger than -Gth2, the process proceeds to step S24, and it is determined whether or not the previously set fluctuation inter-vehicle time Δtf is positive. The fluctuation inter-vehicle time Δtf is an adjustment amount for increasing or decreasing the inter-vehicle time with respect to the base inter-vehicle time Δtb according to the acceleration / deceleration state of the preceding vehicle P or the own vehicle M. If the fluctuation inter-vehicle time Δtf is not positive, the flow shifts to step S25 to determine whether or not the fluctuation inter-vehicle time Δtf is negative. If the fluctuation inter-vehicle time Δtf is 0, the process directly proceeds to step S26, and the sum of the base inter-vehicle time Δtb and the fluctuation inter-vehicle time Δtf is set as the target inter-vehicle time Δtx. When Δtf is 0, Δtx = Δtb. Subsequently, in step S27, the target inter-vehicle distance Dt is obtained from the value of the target inter-vehicle time Δtx. In step S28, the target acceleration Gt is calculated from the deviation ΔD between the target inter-vehicle distance Dt and the current inter-vehicle distance Dr and the relative speed Vr. The value of Gt may be stored as a map value for ΔD and Vr. Gt takes a large value when its absolute value is large when the absolute value of the relative speed Vr and the absolute value of the deviation ΔD are large.
[0019]
If it is determined in step S22 that Gtold exceeds Gth2, and if Δtf is positive in step S24, the process proceeds to step S30, where Δtf is reduced by a predetermined value Δtfx. In the following step S31, if Δtf thus obtained is smaller than Δtfmin, Δtf is set to Δtfmin (which is a predetermined negative value), and the lower limit is guarded to Δtfmin. Thereafter, the process proceeds to step S26, where the target inter-vehicle time Δtx is set, the target inter-vehicle distance Dt is obtained (step S27), and the target acceleration Gt is calculated (step S28).
[0020]
When it is determined in step S23 that Gtold is less than -Gth2, and when Δtf is negative in step S25, the process shifts to step S35 to increase Δtf by a predetermined value Δtfx. In step S36, if Δtf thus obtained exceeds Δtfmax, Δtf is set to Δtfmax (which is a predetermined positive value), and the upper limit is guarded to Δtfmax. Thereafter, the process proceeds to step S26, where the target inter-vehicle time Δtx is set, the target inter-vehicle distance Dt is obtained (step S27), and the target acceleration Gt is calculated (step S28).
[0021]
When the vehicle is accelerating, the target inter-vehicle distance is set to be short. On the other hand, when the vehicle is decelerating, the target inter-vehicle distance is set to be long so that the inter-vehicle control can be performed according to the driver's feeling. Then, sudden acceleration and sudden deceleration at the start of acceleration / deceleration are suppressed. Further, the process of step S24 → 30 → 31 and S25 → 35 → 36, the hunting of the vehicle speed _{V M} of the acceleration and deceleration end is suppressed.
[0022]
After Gt is calculated in this manner, the process proceeds to step S4 shown in FIG. 1, and it is determined whether Vr and ΔD are within the predetermined area A shown in FIG. When the vehicle is within the predetermined area A, it is determined that the preceding vehicle P is decelerating. If it is determined that the preceding vehicle P is not decelerating, the process proceeds to step S5, where the relative acceleration Gr is compared with a predetermined threshold Gth1 (which is a negative value). If the relative acceleration Gr is greater than or equal Gth1, the process proceeds to step S6, and compares the relative speed Vr and the vehicle speed _{V M} of the function value f _{(V M).} For example, f _(V M) = - a _{a × V M + b, a} , b is a both positive constant, positive at the time of low-speed vehicle speed _{V M} is less than b / a, negative at high speeds in excess of b / a Take the value of. Vr is at a higher f _{(V M),} the process proceeds to Step S7. That is, the preceding vehicle P is not decelerating in (step S4), and the relative acceleration Gr is Gth1 more (step S5), and if the relative vehicle speed Vr is f _{(V M)} above (step S6), the control acceleration Gcon The value of Gt set in step S3 is set as it is, and the process proceeds to step S8 to perform acceleration control.
[0023]
If the preceding vehicle P is determined to be decelerating at step S4, [Delta] D in Kan'no control acceleration Gs and proceeds to step S10, it sets the negative acceleration G _A obtained from Vr. When it is determined in step S5 that the relative acceleration Gr is less than Gth1 (in this case, the relative speed Vr is being reduced, that is, the deceleration of the host vehicle M is greater than the preceding vehicle P or the acceleration of the host vehicle M is when the acceleration greater than), the process proceeds to step S11 to set the predetermined negative acceleration _{G B} to Kan'no control acceleration Gs _(where a _G a> G _B). When the relative speed Vr is smaller than f _{(V M)} in step S6, the operation proceeds to step S12 to set the predetermined negative acceleration _{G C} in Kan'no control acceleration Gs by (wherein, _{G A} ≧ G _C> is a _{G B).}
[0024]
After the setting of Gs, the process proceeds to step S13, and the correction calculation of Gs is performed. Specifically, if the state has continued for a predetermined period of time after the transition from steps S10 to S12, Gs is reduced by a predetermined value ΔGs. In step S14, Gt set in step S3 is compared with Gs set in this way. If Gs is equal to or greater than Gt, priority is given to Gt, and the process proceeds to step S7 to set the value of Gt set in step S3 as it is as the value of the control acceleration Gcon. Perform control.
[0025]
On the other hand, when Gs is less than Gt, priority is given to Gs, the process proceeds to step S15, the value of Gs is set as the value of the control acceleration Gcon, and the process proceeds to step S8 to perform acceleration control.
[0026]
As a result, when the preceding vehicle P is decelerating, even when there is a margin in the inter-vehicle distance, it is possible to perform control that gives a sense of security to the driver by performing gentle deceleration. If priority is given to maintaining the inter-vehicle distance, control is performed to accelerate and make the inter-vehicle distance match the target inter-vehicle distance and then decelerate to maintain the relative speed, but by performing gentle deceleration as in this control, By approaching the inter-vehicle distance while decelerating, unnecessary acceleration is not performed, which is effective in terms of fuel efficiency and also matches the driver's sensitivity.
[0027]
When the relative acceleration Gr is less than a predetermined negative value, when the relative speed Vr with respect to the preceding vehicle P is decelerating, when the relative speed is smaller than a predetermined value (when the speed of the host vehicle M is high) Takes a negative value.), The control that matches the driver's sensitivity is performed by suppressing the vehicle from turning into acceleration, thereby suppressing unnecessary acceleration.
[0028]
6 to 8 are actual flowcharts of the acceleration control. FIG. 6 is a flowchart of the main processing, and FIGS. 7 and 8 are flowcharts showing the processing of the switching determination 1 and the switching determination 2, respectively.
[0029]
In step S41, it is determined whether or not the throttle opening θ is positive, that is, whether or not the throttle opening control is being performed. If θ is positive, that is, the throttle opening control is being performed, the process proceeds to switching determination 1 in step S48 described later, and if θ is 0, that is, the throttle opening control is not being performed, the process proceeds to step S42. In step S42, it is determined whether or not the brake oil pressure Pb detected by the oil pressure sensor 51 exceeds a predetermined value P0, that is, whether or not the braking control is being performed. When Pb exceeds P0, that is, when the braking control is being performed, the process proceeds to switching determination 2 in step S49 described below. On the other hand, when Pb is equal to or less than P0, that is, when the braking control is not being performed, the process proceeds to step S43, and the values of the braking control counter ib and the throttle control counter it are reset to 0. In a succeeding step S44, the value of the control acceleration Gcon is compared with a predetermined threshold value Gth4. This Gth4 takes a predetermined negative value. When Gcon exceeds Gth4, it is determined that the throttle control needs to be performed, and the process proceeds to step S45 to increase the throttle opening θt by Δθt, and to set the target brake control oil pressure Pt to the non-braking oil pressure P0. Set to. In a succeeding step S46, the operations of the throttle motor 31 and the brake actuator 4 are controlled according to the obtained θt and Pt, and the process ends.
[0030]
In step S44, when Gcon is equal to or smaller than Gth4, it is determined that the braking control needs to be performed, and the process proceeds to step S47 to increase the brake control oil pressure Pt by ΔPt and to set the target throttle opening θt in the fully closed state. A certain value is set to 0, and the process proceeds to step S46 to perform operation control.
[0031]
In the switching determination 1 in step S48, first, the value of the braking control counter ib is reset to 0 (step S51). Subsequently, the value of Gcon is compared with a threshold value Gth3 (step S52). This Gth3 takes a negative value. If GCON is more Gth3, by comparing the the _G M -G1 minus the contribution G1 of the acceleration obtained by controlling the throttle from the acceleration _{G M} of the vehicle (θ) (θ) Gcon Then, it is determined whether or not Gcon exists within the acceleration range obtained only by the throttle control (step S53). Here, G1 (θ) is an estimated value considering the case of a downhill. If G _M -G1 the (theta) exceeds the Gcon determines that if there is the possibility, to 1 adds the value of the throttle control counter it (step S54). Then, in a step S55, it is determined whether or not the value of it exceeds the threshold value itth. If it is determined that it is less than itth, the process proceeds to step S56 to continue the throttle control, and the target throttle opening θt is increased or decreased according to the difference between Gcon and Gr, and the target brake oil pressure Pt remains P0. maintain. When it is determined that it is equal to or more than itth, it means that the target acceleration has not been achieved by the continuation of the throttle control. Therefore, the process proceeds to step S57, the target throttle opening θt is set to 0, and the target brake oil pressure Pt is set to P0 + ΔPt. Is set, and the operation shifts to brake control.
[0032]
When _{the G} M -G1 (theta) is less than or equal to Gcon in step S53, it determines that it is possible to achieve Gcon only throttle control to reset the it to 0 (step S58), to step S56 Then, the throttle control amount θt is set.
[0033]
If it is determined in step S52 that Gcon is equal to or smaller than Gth3, it is determined that there is a high possibility that the target acceleration (actually, a deceleration command) cannot be achieved by throttle control as compared with other cases, and the process proceeds to step S59. it was, first reset it to zero, comparing the vehicle acceleration _G contribution of the acceleration obtained by controlling the throttle G2 from _M (theta) minus _G M -G2 and (theta) GCON Then, it is determined whether or not Gcon can be achieved at the deceleration obtained when the throttle is fully closed (step S60). Here, G2 (θ) is an estimated value in consideration of a flat road, and takes a value smaller than G1 (θ).
[0034]
If G M _-G2 the (theta) exceeds the Gcon, it is determined that the throttle control is a case of controlling the acceleration Gcon a deceleration command can not be achieved, the target throttle opening θt and proceeds to step S57 Is set to 0, the target brake hydraulic pressure Pt is set to P0 + ΔPt, and the process shifts to brake control. On the other hand, if G M _-G2 (θ) is less than Gcon, it is determined that the control acceleration Gcon a deceleration instruction by the throttle control could be achieved, the throttle control amount proceeds to step S56 [theta] t Make the settings for
[0035]
In the switching determination 2 of step S49, first, the value of the throttle control counter it is reset to 0 (step S71). Subsequently, the value of Gcon is compared with a threshold value Gth3 (step S72). This Gth3 is the same as the value used in step S52 described above. If Gcon is Gth3 below, G _M obtained by subtracting the contribution G3 (Pb) of the acceleration obtained by the brake control from the acceleration G _M of the vehicle (actually takes a negative value because it is the deceleration) - By comparing G3 (Pb) with Gcon, it is determined whether or not Gcon exists within the deceleration adjustment range only by the brake control (step S73). Here, G3 (Pb) is an estimated value considering the case of an uphill. G _M -G3 (Pb) is in the case of less than Gcon determines that if there is a possibility that out of the deceleration adjustment range, to 1 adds the value of the braking control counter ib (step S74). Then, in a step S75, it is determined whether or not the value of ib exceeds the threshold ibth. If it is determined that ib is less than ibth, the process proceeds to step S76 to continue the brake control, the target brake hydraulic pressure Pt is increased or decreased according to the difference between Gcon and Gr, and the target throttle opening θt remains 0. maintain. If it is determined that ib is equal to or more than ibth, it means that the target acceleration has not been achieved by the continuation of the brake control. Therefore, the process proceeds to step S77 to set the target brake oil pressure Pt to 0 and to set the target throttle opening θt to Δθt. And then shift to throttle control.
[0036]
When _{the G} M -G3 (Pb) is less than or equal to Gcon in step S73, it determines that it is possible to achieve Gcon only brake control to reset the ib to 0 (step S78), to step S76 Then, the target brake hydraulic pressure Pt is set.
[0037]
When it is determined in step S72 that Gcon exceeds Gth3, it is determined that there is a higher possibility that the target acceleration cannot be achieved by the brake control as compared with other cases, and the process proceeds to step S79. reset to the own vehicle _G M -G4 from the acceleration _{G M} obtained by subtracting the contribution G4 (Pb) of the acceleration obtained by the brake control and (Pb) by comparing the GCON, the deceleration adjustment range of the brake It is determined whether or not Gcon exists (step S80). Here, G4 (Pb) is an estimated value in consideration of a flat road, and has a relationship of 0> G4 (Pb)> G3 (Pb).
[0038]
If G _M -G4 (Pb) is less than Gcon, the brake control is determined to be a case where the control acceleration Gcon can not be achieved, and the target throttle opening θt to Δθt and proceeds to step S77, the target The brake hydraulic pressure Pt is set to P0, and the operation shifts to the throttle control. On the other _hand, if G M -G4 (Pb) is greater than or equal Gcon, it is determined that the control acceleration Gcon by the brake control may be able to achieve, to set the brake control amount Pt and proceeds to step S76 .
[0039]
By performing the switching control as described above, the switching between the brake and the throttle control can be rapidly performed, and particularly, it is possible to suppress the occurrence of the hunting of the control due to the delay of the switching at the time of climbing up or downhill. it can.
[0040]
In the above description, an example has been described in which the deceleration of the preceding vehicle P is determined based on the map. For example, the determination may be made from the acceleration of the preceding vehicle P itself, or the lighting of the brake lamp or the hazard lamp of the preceding vehicle P may be performed. The determination may be made by image input means or an optical sensor or the like.
[0041]
【The invention's effect】
As described above, according to the present invention, not only the inter-vehicle distance between the preceding vehicle and the host vehicle, but also the acceleration / deceleration state of the host vehicle is adjusted according to the acceleration / deceleration state, thereby matching the driver's sensitivity. Travel control can be performed.
[Brief description of the drawings]
FIG. 1 is a schematic view of a vehicle equipped with a travel control device according to the present invention.
FIG. 2 is a block configuration diagram of FIG. 1;
FIG. 3 is a diagram showing states of a preceding vehicle and a host vehicle.
FIG. 4 is a flowchart showing a main process of control of the apparatus of FIG. 1;
FIG. 5 is a flowchart showing details of a target acceleration calculation in FIG. 4;
FIG. 6 is a flowchart of a main process of the acceleration control in FIG. 4;
FIG. 7 is a flowchart illustrating a process of switching determination 1 of FIG. 6;
FIG. 8 is a flowchart illustrating a process of switching determination 2 in FIG. 6;
FIG. 9 is an area map used for a preceding vehicle deceleration determination.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 laser radar sensor 2 control ECU 3 engine 4 brake actuator 20 vehicle control ECU 21 engine ECU 22 brake ECU 31 throttle motor 50 wheel speed sensor 51 Hydraulic pressure sensor, 52: G sensor, 53: throttle opening sensor, 60: travel control device, P: preceding vehicle, M: own vehicle.

Claims (6)

In a travel control device that detects a preceding vehicle and controls the inter-vehicle distance,
A target inter-vehicle distance and a target acceleration / deceleration state of the host vehicle are calculated based on the inter-vehicle distance between the preceding vehicle and the host vehicle, a relative speed, and the host vehicle speed, and the target inter-vehicle distance is calculated according to the acceleration / deceleration state of the preceding vehicle or the host vehicle. And a target acceleration / deceleration state. 2. The travel control device according to claim 1, wherein even if the inter-vehicle distance to the preceding vehicle is longer than the target inter-vehicle distance, when the deceleration of the preceding vehicle is detected, the cruise control device performs slow deceleration. The travel control device according to claim 1 or 2, wherein the target inter-vehicle distance is set shorter than other cases during acceleration of the own vehicle. The travel control device according to any one of claims 1 to 3, wherein the target inter-vehicle distance is set to be longer than other cases during deceleration of the own vehicle. The method according to any one of claims 1 to 4, wherein when reducing the required acceleration during the throttle control, the acceleration obtained when the throttle is fully closed is estimated, and when the required acceleration is lower than the required acceleration, the control is switched to the brake control. The travel control device according to any one of the preceding claims. 6. The method according to claim 1, wherein when the required acceleration is increased during the brake control, the acceleration obtained when the brake is turned off is estimated, and when the required acceleration exceeds the required acceleration, the control is switched to the throttle opening control. The travel control device according to any one of the preceding claims.

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